Sound reproducing device



May 9, 1933. A. McL. NICOLSON 1,908,172

SOUND REPRODUCING DEVICE Filed May 20, 1930 FIE-3%.].

lNVENTOR A/cxander M Lcun /Y/c0/5 an.

BY b A/K W ATTORNEY Patented May 9, 1933 ,-u-m1 STATES PATENT OFFICE ALEXANDEB KCLEAN NICOLSON, OF NEW YORK, N. Y., ASSIGNOR TO COMMUNICATION PATENTS, INC OF NEW YORK, N. Y., A CORPORATION OF DELAWARE scum) nnrnonocme DEVICE Application filed May 20,

This invention relatesto the reproduction of sound from electrical vibrations, and particularly to the reproduction of sound having the same phase at any instant.

An object of this invention is to reproduce sound at many points, the sound having the same phase and amplitude at each point.

Anotherobject of theinvention is to reproduce sound having good quality and constant phase displacement over a definite area.

In public address systems for auditoriums or outdoor presentations, in which a binauml or directional eflect is desired, it is neces sary to produce along a certain line or in a definite plane, sound from a particular pickup device or microphone. These sound waves should be initiated in phase and at a constant pressure; to insure a good bin'aural effect over a considerable area. This may be accomplished electrically by connecting a group of loud speakers arranged along a line radiating from the sound source, in series or parallel with the proper polarization of the fields. However, the present invention contemplates reproducing sound from a mechanical oscillating medium which is driven electrically. In other words, a single electrical unit or, two units operating as a single unit, is arranged. to drive a medium such as a tensioned wire from which sound is radiated from acoustic radiators disposed at uniform intervals along its length. In such an arrangement each point of propaga' tion will be activated simultaneously, thereby projecting sound at the same instant. Also, each'direct propagation means will be actuated with the same force and, therefore, project sound having the same amplitude at each point. p

The driving medium or wire is tensioned so that its resonant frequency is as high as possible in the audio range, thereby decreasing acoustic resonance and motional impedance. The driving units may have electrodynamic or electromagnetic units or piezo-electric motors, to the moving ele ments of which the actuatin wires are attached. The wire may be in Tree air or contained within a cylindrical container such 1930. Serial No. 453,987.

as a pipe with outlets therein to permit the attaching of sound radiators or acoustic diaphragms.

The details of the invention will be more fully understood by reference to the accompanying drawing in which:

Figure 1 is a partial cross-sectional view of a single Wire construction;

Fig.2 is a cross-sectional view of a driving unit;

Fig. 3 is a cross-sectional View of a double range driving unit;

Fig. 4: is a double wire system in which sound is produced within a cylindrical container; and

Figs. 5 and 6 are views of two types of sound radiating mediums which may be employed in the above systems.

Referring particularly to Fig. 1, driving units 5 and 6 with their feeding conductors 3 and 4 are shown at the extremities of a cylindrical housing in the form of a pipe divided into two sections 7 and 8, respectively. These sections. are joined together b a threaded coupling 9, which is the means or tensioning a wire 11 connecting the two units 5 and 6. The wire 11 may be free and continuous between operating elements at units 5 and 6 or may consist of two separate wires attached to fixed resilient members held in position by the coupling 9. The degree of tension desirable depends upon the separation between units 5 and 6, but is preferably not less than that required to make the frequency of the mechanical resonance above the audible range. Connected to thewire at definite intervals along its length are sound radiators 12 and 13, in theform of cone shaped members. These radiators are firmly attached to the wire 11 so that they vibrate longitudinally with the wire 11, the radiators being flexibly held in position by stops 15 which ma be composed of soft sponge rubber or the like The two driving members 5 and 6 work in synchronism, that is, any force directed in the right hand direction by unit 6 will be an mented or reinforced by the unit 5 acting in the same direction.

In Fig. 2 a driving unit 17 is shown with its diaphragm armature 19 similar to a telephone receiver unit attached to a driving wire 18. The conductors 2 may be connecte to the output of an amplifier system. In this modification of the system of Fig. 1, two sound radiators and 21 are connected at one point on the wire 18 with a r' id couplin 22. These sound radiators may com of stifl paper, light wood or any light material having acoustic radiation properties and arepreferably formed into hollow conical shaped extensions. They not only vibrate about their mounting points in the pipe, as shown in Fig. 1, but also have vibrations induced therein along the direction of their principal axes. The 7 8 of the stem in Fig.1,orpipe23 o .2,maybeo steel or cast iron or of non-metallic material such as hard rubber or Bakelite. Screws 24 connect the unit 17 with the ipe 23 and'also are employed for tensioning e wire 18, the wire being either connected to the diaphragm armature of a similar unit or to a fixed resilient support at the end of the pipe 23. These diaarmatures and supports for the teri 1 of the wires are stretched and of comparatively heavy material to enable the wire which has a comparatively small mass to be pro tensioned.

Ini, ig. 3 a double driving unit is shown wifli tensio'uing screws 25 arranged dijlerent manner from that in Fig. 3. ilnit. 26;,is shown two sets of driving coils 27 and 28 and respective armatures 29 30. in the form of levels with andlong sections such that the a htiiei ropar tensioning'pull-to be a [be energized from conductors 34, and m y he energised from conductors 39. 29.drives a tensioned wire 31 to connected a sound-radiator 32 at is v pqiitt'dll, Armature v80 drives a tensioned ,37. connections are made intheaamemannerasinthesystemsshownin Fig. 1 andtlbut the radiators 32 and are on avers or acoustic diaphragms, across the whole cross-section of r and ,act as a damping w 'P s myb y. 14": A8 levers, 'com riseastripmomi: at diametricalposition's within th radiators 32 and 30 e pipe. preferably hollow, have two modes of vibration as in Fig. 2, one be about the mounting pointsin the pipe, an

theotheralongtheir rincipalaxes.

Inthesys'temof 3,the armature29 ,with its associatecoils maybeconstructed soastoberesonantatafrequency within the higher frequency range of the audio fw quency band, while the armature 30 with its associate coils 28 may be ad'usted tobe resonant. at a frequency in the ower portion of sections thereof. Coils.

, ternate diap hr s r' The site sides o2 the dfiphragtu as a fastening. Theses rings ma ofthecoiltype I of aper.

shows a form of sound radiator of r the an-shaped type in which. a paper has means the audible range. Further improvement may be made by impreming the rticular range of frequencies on the partic ar speaker constructed for that range. In such a case, the radiators 32 and 36 ma be positioned on the .same side of the pipe or reproducing a com le'te range of audible frequencies of muc better quality than can be realized from a sin is unit. I

With the units placed on o sides of the pipe as shown, they may driven from spurces of sound having various phase relationships for use in a large auditorium wherein the auditorium is divided into sections, each section having the same directional effects. Radiator 32 maybe located onone side of a division,-and radiator 36' on the other, each having an individual and distinct input. Such an auditorium system is disclosed in my cogefiding application Serial No. 453,003 filed y 1 1930. A

In Fig. 4 another modification of a sound reproducing system is disclosed. The driving units 40 and 41 maybe the sameas the unit shown above inFig. 3, the double driving units being placed at the extremities of a i 42, and energized over conductors 48 and-g: respectively. The acoustic-radiation of this system is somewhat different from that ofthe others shown above. A-tensioned wire 43 connected to alternate internal diap 44, and a tensioned wire 45 is connected to al- I ternateinternaldiaphragms 46 and 47s, The

dri' ,wire43 assesthro diahragms 46 47 and t driving vi ire 4 5 passes through the diaphragm 44. without any connection between the respective wires and diaphragms. -.Sound is produced within i the pipe b the respective propaga through holes 50111 which have a horn shapled for obtain extension 51 may be driven from two units whici are resonant in difierent ortions, of the audio-rs each of whi will produce in alternate being reproduced will combine within the respective sections and be projected 1y through the. horns 51. .To obtain the si'sper elasticity and damping. elect iii the 53 are shown onpppoormaybeinthe ormoff twashersorlayerl been folded and comp along-one edge to a point which is attached to a driving wire 55. Four sections 56, 57 58 and 59 have been. brought together in this manner and disposed around the wire to form the foursectional radiator, as shown.

a P P P asms high quality reproduction at that particular frequency. The two portions of the. band o t a da directions street. The 1rd In Fig. 6 a cup-shaped radiator is shown which is connected to a driving wire 60 by a lock collar 61. This radiator ias a flat diaphragm 62 which is common to both cupshaped portions 63 and 64. This type of radiator is especially desirable for use without the pipe construction, while the radiator of Fig. may be used with a pipe which has been cut away to ermit access to the wire at four points. e ipe will pass through the serrated portions 0 t e radiator.

Inmusing a s stem as above disclosed in an auditorium, t ey ma be constructed in lengths of 10, or eet, and laid along the floor, under the seats, alon the wall edges or along the upper corners o the auditorium, with the sound radiators extending into the room. For outdoor use the ma be positioned on standards or laid a ong t e ground in a radial direction from the source of sound. By having compound units spatially disposed to form listening areas separating various sections, the series of radiators on one side of the pipe may be projecting sound in one phase, while those on the other side of the pipe may be projecting sound of a different phase. The compound driving unit may also be projecting sound into the same area, different groups of radiators projectin different ranges of frequencies within t e audlble Although this invention has been disclosed in one particular embodiment, it is to be understood that it is adaptable to systems within the scope of the appended claims.

What is claimed is:

1. In a sound reproducing system, a pair of oppositely disposed electrical driving units having movable members, means for mechanically connecting said members, and means connecting said units for tensioning said mechanical connecting means, said tensioning means enclosing said connectin means.

2. In a sound reproducing evice, a plural-electrical driving unit having two sections each responding to a different range of frequencies, means for radiatin sound waves having frequencies lying in t e ranges to which said sections are responsive, means for actuating said radiatin means from each of said units, and means or enclosing and tensioning said radiating means.

3. In a sound reproducing device, two electrical driving units oppositely disposed, an

armature for each of said units, means for connecting said armatures, said armatures being driven in synchronism, a hollow cylindrical member separating said units and containing said connecting means, and means within said cylindrical member attached to said armature connecting means for transforming mechanical vibrations into sound waves.

4. In a sound reproducing device, a plurality of electrical driving units positioned apart from one another, an armature for each 0 said units, a mechanical connecting member between said armatures of said units, a hollow connecting member between said units for tensioning said connecting means, and means within said hollow member and projecting through openings therein for transforming mec anical vibrations into sound waves.

5. In a sound reproducing device, a plurality of electrical drivin units positioned apart, an armature in eac of said units, a mechanical connecting means between said armatures, said units being connected to drive said armatures in synchronism, a hollow member separating said units and containmg and tensioning said connecting means, armatures positioned within said hollow member and attached to said mechanical connecting means, and radiating members attached to said armatures extending through said hollow member for transforming mechanical vibrations into sound waves.

6. In a sound reproducing device, a pair of electrical driving units positioned apart and adapted to o erate in synchronism, a hollow rigid mem er for varying the distance between said units, an operating diaphragm at each of said units mechanical means for connecting said diaphra ms, said means being tensioned by said hol ow rigid member, and means extending through openings in said rigid member and attached to said mechanical connecting means for transforming mechanical waves into sound waves.

7. In a sound reproducing device, a plurality of oppositely disposed electrical driving units, an armature for each of said units, means for connecting said armatures, a hollow rigid member separating said units and containing said connecting means, a plurality of diaphragms equall disposed within said hollow member an alternately attached to said connecting means, said diaphragms transformin mechanical waves into sound waves and orming air chambers therebetween.

Witness my hand this 14th da of May 1930, at Newark, in the county of ssex, and State of New Jerse ALE NDER IcLEAN NICOISOI. 

